IPTV (Internet Protocol Television) is a generic term for a service which performs digital TV broadcasting over an IP network or delivers content such as an image, or for the broadcasting technology. There is VOD (Video On Demand), as the content delivery service, which provides content in response to a delivery demand from an end device.
A conventional IPTV delivery system is a system in which both a control message and an AV stream of content are transmitted over the same bidirectional IP network. The system is disclosed in Patent Document 1, which suitably changes a deliver form and then delivers the content, in the content delivery system. In the content delivery system disclosed in Patent Document 1, a delivery server and a client terminal are connected to each other over a network, for example, over the Internet. Upward information, such as a request from the client terminal for delivery, and downward information, such as the content delivered from the content server are all exchanged over the Internet.